How do people mine for cryptocurrencies?

Cryptocurrencies are mined by solving complex mathematical problems. The first miner to solve the problem gets to add the next block to the blockchain and is rewarded with a certain amount of the cryptocurrency. The difficulty of the mathematical problems gets harder as more miners join in the race to solve the next block, and the rewards get divided among more miners. This means that it becomes increasingly difficult to mine for cryptocurrencies as time goes on.